Slice is a new app that aims to make receipt-keeping and package-tracking so simple you don't even need to do anything.

Plug in your email address one time, and Slice digs through years of e-receipts and turns them into itemized products on goslice.com.

Since Slice monitors your email account for receipts (don't worry, it's extremely secure and automatic), you never have to find a tracking number again.

Slice handles new things you order too, giving you one stop shop access to tracking, receipts, shipping info, and even customer service numbers relevant to your order. And it's all free. No ads, no fuss.

You'll even get notified of a price drop on something you just purchased, and you're eligible to ask for a partial refund.

Slice launched on the web in May, and has processed more than 4 million purchases already. The mobile app comes out today and has all the features of the web version, plus push notifications for when packages ship or get delivered.

While Slice is already a remarkably easy service to use, CEO Scott Brady has lofty goals in mind. "When the iPhone 4S launched, we were able to see exactly what colors and sizes were being ordered in real time. Since Slice monitors your email account, we get real time data on what people are purchasing, and when."

Brady also noted that since receipts are becoming digital even at brick and mortar stores, Slice will eventually be able to track every purchase you ever make. This includes flights, hotels, and more, where Slice will have special increased functionality.

Clearly, Slice has some pretty valuable data on its hands. The best way to understand Slice is to see it for yourself, so check out our full walkthrough below.